Bird 'flu in the USA

A virulent form of bird flu has been discovered on a chicken farm in Texas, USA. The outbreak, originally classified by the USDA as low-risk, was identified through genetic testing yesterday morning as being 'highly pathogenic'.

The US Centers for Disease Control (CDC) has enacted a nationwide federal response system to deal with the emergency, although it considers the chances of human infection low. Government officials have moved to reassure the public that the description of 'highly pathogenic' has to do with the level of threat to poultry, not humans.

Nonetheless, all exports from Texas have been halted and more than 6,600 birds were destroyed in Texas over the weekend. Russia, the largest importer of US chickens, has banned poultry from the state. Other countries were expected to follow suit.

The strain is a weaker version of the H5N1 form that jumped from birds to humans this year in south Asia resulting in at least 22 deaths. The H5N1 virus was also responsible for the 1997 bird flu outbreak in Hong Kong, where the disease spread to humans. The Texas version has sprung up independently and was not imported from Asia, officials said.

This latest case of bird influenza turns yet more unwanted attention on the state of North America's meat production. A case of bird flu was discovered earlier this month on a Canadian poultry farm, and international authorities responded by banning all imports of poultry and related products from Canada. Both Chinese and Brazilian authorities said current consignments of Canadian poultry would either be returned or destroyed.

The Canadian poultry farm is currently in the process of slaughtering all of its 16,000 chickens using carbon dioxide and the farm will be under quarantine until all evidence of the disease is eradicated. Of the five people exposed to the virus on the farm, two individuals have gone on to develop mild flu-like symptoms. Health officials said that there was no laboratory confirmation that any of the symptoms reported are linked to the infected chickens.

"However, the pattern of symptoms we are seeing is consistent with those described in human infections of at least one type of H7 influenza virus in other parts of the world," said Andrew Larder, medical health officer of the province's Fraser Health Authority at a news conference.